Motor Evoked Potentials Study of the Facilitation and ReciprocalInhibition Induced by Motor Imagination in the Thumb Muscles

Yang, Hyun Duk; Son, Il Hong; Suk, Seung Han; Lee, Sung Soo

Ann Clin Neurophysiol > 2003 ;5(2) > Article

Ann Clin Neurophysiol. 2003; 5(2): 187-191.

Hyun Duk Yang, Il Hong Son, Seung Han Suk, and Sung Soo Lee

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Purpose: MEPs elicited by transmagnetic stimulations of the motor cortex are facilitated by voluntary muscle contraction.We evaluated the effects of the imagination of the movements on latencies of MEPs and reciprocal inhibitionby using transmagnetic stimulations.
Methods: Twenty two healthy volunteers(eight men and fourteen women) were studied. TMSs were delivered at restand during imagining abducting or adducting right thumb. A stimulator with a round coil and a fixed intensity of 80%of maximum was used to evoke MEPs. MEPs were evoked by magnetic stimulations over the scalp and cervicalspine(C7-T1), and central motor conduction times(CMCT) were calculated by subtracting the latency of compoundmuscle action potentials(CMAPs) obtained by stimulating over the cervical spine from that obtained by stimulating overthe scalp. The motor evoked potentials were recorded from right abductor pollicis brevis muscle(APB) and adductorpollicis muscle(AP) simultaneously.
Results: Imagination of abduction resulted in a shortened latency of the CMAPs in APB, and a prolonged latency inAP. Imagination of adduction resulted in a shortened latency in AP, and a prolonged latency in APB. But the imaginationcaused no significant change in the latency of CMAPs elicited by stimulation over cervical spine. Therefore, thechanges of the CMCTs account for these latency changes with imagination of movement. With the imagination ofabduction, there are significant reduction of the CMCT

Key words: Motor imagination, Reciprocal inhibition, Transcranial magnetic stimulation, Central motor conduction time